1. Field of the Invention
The present invention relates to a communications network, and more particularly, to a method for screening a signaling message in a No. 7 signaling network.
2. Background of the Related Art
The ITU-T signaling system No. 7 is typically used as a signaling system between exchanges in a mobile communication network. Such a signaling system No. 7 includes a signaling message screening function. This function prevents an unfriendly or unexpected signaling message from being introduced into a local signaling network of a service provider, and is generally carried out at a gateway signaling point when the above signaling network is interlocked with a signaling network of another service provider.
The signaling message screening function of the signaling system No. 7 will be described according to an example of the construction of the signaling system No. 7 illustrated in FIG. 1. Referring to FIG. 1, supposing that signaling points A, B, and C belong to a service provider X, and that signaling points D, E, and F belong to a service provider Y. Further, assume that a signaling message is transmitted from signaling point A to signaling point F, and that the signaling message screening function is carried out at signaling points D and E of the service provider Y. Finally, assume that signaling link sets in the signaling network are all available.
A signaling message generated from signaling point A is routed to adjacent signaling points, specifically signaling point B or C, in order to be transmitted to signaling point F. After receiving the message, the adjacent signaling point carries out a signaling message discrimination function. This is done at A message discrimination unit with respect to the signaling message received from the signaling network. Since the destination point of the signaling message is not the signaling point having received this signaling message, a routing process is carried out in order to transmit the signaling message to the final destination signaling point. This is done by transmitting the same to a message routing unit, whereby the signaling message is received from a gateway signaling point of the service provider Y, that is, the signaling point D or E.
In Message Transfer Part (MTP) level 3 of the gateway signaling point that received the signaling message, a routing or distribution is carried out by analyzing (discriminating) the received signaling message. This will be described with reference to FIG. 2.
As shown in FIG. 2, the message discrimination unit 1 identifies the final destination of the signal message by analyzing the message received from a signal link of MTP level 3. It then transmits the received message to a message screening unit 2.
In a disabled state of the signaling message screening function, the message screening unit 2 preferably performs one of two possible tasks after receiving the above signaling message. First, if the final destination identified by the message discrimination unit 1 is non-local, the message screening unit 2 transmits the signaling message to a message routing unit 4 for routing the same to a signal route connected to an adjacent signaling point. This is done to transmit the signaling message to the final destination. If the identified final destination is local, on the other hand, the message screening unit 2 transmits the signaling message to the message distribution unit 3, which transmits the same to a local user part (level 4).
In an enabled state of the signaling message screening function, the message screening unit 2 carries out screening of the above signaling message.
Where the received signaling message has passed through the screening function, if the final destination identified by the message discrimination unit 1 is non-local, the signaling message is transmitted to the message routing unit 4 for routing the signaling message to a signal route connected to an adjacent signaling point. This is done to transmit the signaling message to the final destination. If, however, the identified final destination is local, the signaling message is transmitted to the message distribution unit 3, which transmits the signaling message to a local user part (level 4).
Where the received signaling message has not passed through the screening function, the corresponding signaling message is determined to be non-transmittable and is abandoned, and a signaling network management unit (MTP level 3) of a local signaling point is notified of the abandonment of this signaling message.
In the case that the signaling message received by the signaling message screening function is abandoned at a gateway signaling point, the local signaling network management unit recognizes that this signaling message has been abandoned. This information, however, cannot be recognized by the originating point of the signaling message.
Thus, in a signaling network as shown in FIG. 1, when the signaling message is abandoned at the signaling point D or E by the signaling message screening function, the signaling point (D or E) recognizes that the signaling message is abandoned. A signaling point of other service provider network (X), and originating point A, however, cannot recognize this fact. Hence, the originating signaling point A continuously sends the signaling message.
This causes the amount of loads of the signaling network to be increased during traffic transfer due to the signaling message abandoned by the signaling message screening function. Because the originating point cannot know the reason thereof, it is difficult to take proper action to correct this problem.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
An object of the present invention is to provide a method for screening a signaling message in a No. 7 signaling network that overcomes the limitations and disadvantages caused by problems with the related art.
It is a another object of the present invention to provide a method for screening a signaling message in a No. 7 signaling network which is capable of preventing transmission of a signaling message abandoned by the signaling message screening function at a gateway signaling point by notifying an originating signaling point of the screening information on the signaling message.
To achieve at least these objects in whole or in parts, there is provided a method for screening a signaling message in a No. 7 signaling network, which includes a first step of generating a MSI (MTP Screening Information) message containing the screening information on a signaling message to be abandoned during signaling message screening and transmitting the same to an originating signaling point; and a second step of preventing transmitting of the signaling message to be abandoned using the screening information contained in the MSI message.
To achieve at least these objects in whole or in parts, there is provided another method for screening a signaling message in a No. 7 signaling network, which includes a first step of generating a Message Transfer Part (MTP) Screening Information (MSI) message containing the screening information for a non-transmittable signaling message during a signaling message screening function, a second step of transmitting the MSI message to an originating signaling point, and a third step of preventing the transmission of the signaling message to be abandoned by using the screening information included in the MSI message.
To achieve at least these objects in whole or in parts, there is provided another method for screening a signaling message at a gateway signaling point in a No. 7 signaling network, which includes a first step of screening a signaling message inputted into a local station, and a second step of transmitting screening information to an originating point of a signaling message determined to be non-transmittable during the screening.
To achieve at least these objects in whole or in parts, there is provided another method for screening a signaling process at an originating signaling point in a No. 7 signaling network, which includes a first step of receiving a prescribed message having screening information among signaling messages inputted from other signaling points, a second step of storing the screening information in memory, a third step of determining whether a signaling message is transmittable, referring to the stored screening information, and a fourth step of preventing transmitting of the signaling message to be abandoned.
To achieve at least these objects in whole or in parts, there is provided a message discrimination system of a No. 7 signaling network, which includes an analyzer circuit to receive a signaling message and determine if the signaling message is a message screening information (MSI) message, a memory coupled to the analyzer circuit to receive and store the signaling message determined to be a MSI signaling message, and an output circuit coupled to transmit a state of the memory to a signaling network manager.
To achieve at least these objects in whole or in parts, there is provided a signaling message screening information message for a No. 7 signaling network, which includes a point code, a service information octet, a screening cause, a heading label, and a routing label, wherein the message screening information message prevents transmission by an originating signaling point of a signaling message to be abandoned, and wherein the heading label comprises first and second heading codes that allocate and use unused values among the values defined in recommendation ITU-T, Q.70x.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.